On Thu, 17 Sep 2015, Zhenyu Zhang wrote: > 1) How to apply such a condition, in which the condition variable's value > not depend on x,y,z and t, but > on other primitive variables. I wonder now how to implement it with > ParsedFunction yet.
So there's no direct dependence on t, but there's an indirect dependence via the dependence on other primitive variables? > 2) Generally we set up the BC objects with pre-specfied values or > fucntions before the loop of time marching or iteration. Now with > TransientNonlinearImplicitSystem, is it possible to add the above > real time setup of boundary condition into the loop? If you use a ParsedFEMFunction, you can easily get your boundary condition to depend on any primitive variable in the same system. *However*, the boundary conditions will only be re-evaluated when you call System::reinit_constraints() (or anything that calls it, like EquationSystems::reinit()). If your system isn't very sensitive to the boundary conditions, you can probably live with the small-constant-times-deltat error you'll get by just doing a reinit_constraints() at the start of every time step. If your system is sensitive to the boundary conditions, so lagging them gives an error (and/or stability restriction on deltat!) which is too severe, you'll need to reinit_constraints() within your nonlinear solver loop. If your system is *very* sensitive to the boundary conditions, then even a reinit_constraints() within the nonlinear solver might not be enough (it ought to add a sub-quadratic term to your convergence behavior) and you'll need to handle constraints manually within your residual. --- Roy ------------------------------------------------------------------------------ Monitor Your Dynamic Infrastructure at Any Scale With Datadog! Get real-time metrics from all of your servers, apps and tools in one place. SourceForge users - Click here to start your Free Trial of Datadog now! http://pubads.g.doubleclick.net/gampad/clk?id=241902991&iu=/4140 _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
